713 



It has often been observed that the starch grains in resinosis succumb 

 to Hque faction just as in gummosis. Starch certainly furnishes a large part 

 of the resin in the exudation. Wiesner^ states, for example, that resin bodies 

 exist within the medullary ray cells of foliage trees and possess the structure 

 of the starch grains. These rarely turn blue with the use of pure iodine but 

 do so more often with iodine and sulfuric acid. With the use of ammoni- 

 acal cuprous acid they give the cellulose reaction ; they react to ferric chlorid 

 like tannin. Wiesner, therefore, concludes from his investigations that a 

 large amount of the resin, occurring in nature, arises from starch grains 

 themselves, or from starch grains which have been changed into tannin. He 

 considers the tannin to be a connecting link between the cellulose and resin. 



We find in Nottberg's" very thorough work on resin pockets the proof 

 that even in the exudation of resin an abnormal parenchyma wood is formed 

 which succumbs to resinosis and liquefaction. Nottberg proves that, as a 

 result of any injury, whatever, which extends to the cambium, this responds 

 with the production of a "tracheidal 

 parenchyma" which gradually passes 

 over again into the normal tracheids. 

 The tracheids of the sap wood which, 

 as a result of the injury, come into 

 contact with the outer world, stop up 

 their lumina with a mass resembling 

 wound gum, which is insoluble in 

 alcohol but dissolves after treatment 

 with Schultz's mixture. Usually res- 

 inosis occurs at the same time in the 

 wood body. The different cells of 

 the diseased parenchyma immediately 

 after their production begin to form 

 resin internally (resin cells). The 

 membranes of the new^ cells of the tracheidal parenchyma liquefy very early. 

 The unthickened elements, on the other hand, as long as they are retained, 

 constantly show only the cellulose reaction. In the resin cells a definite layer 

 may be recognized in which the resin is formed (resinogenous layer, Fig. 

 157). Nottberg, from whose book the figure is taken, leaves undecided what 

 this resinogenous layer is; "a developmental product of the membrane, or of 

 the cyptoplasm." 



The pathological formation of resin may be considered the most exten- 

 sive process of liquefaction at present known in the vegetable kingdom. It 

 existed in the tertiary period as well as now, for Conwentz states in his 

 monograph on the Baltic Amber trees (Pinus succinifera, Conw.), which 

 has excellent illustrations, "there was scarcelv one healthv tree in the whole 



Fig-. 157. Cells of the tracheidal paren- 

 chyma of Pinus Strobus with the resin- 

 ii'erous layer rsg; ht resin drops. (After 

 Nottberg-.) 



1 Sitzung-sbericht d. Akad. D. Wissensch. zu Wien, Vol. 51. 



2 Nottberg, P. Experimentale Untersuchur.gen uber die Entsteluing von Harz- 

 gallen und verwandter Gebilde bei nnseren Abietineen. Zeitsch. f. I'flanzenkr. 1S97, 

 p. 1.S.3 ff. TTifM- nuch weitere Literatur. 



